/Engine/Plugins/Developer/AnimationSharing/Source/AnimationSharing/Public/AnimationSharingManager.h
Retrieves a blend instance, and sets up a blend between a currently running On-Demand instance and another one which was started this frame
uint32 SetupBlendBetweenOnDemands ( uint8 FromOnDemandInstanceIndex, uint32 ToOnDemandInstanceIndex, uint32 ActorIndex )